Use package:sky imports consistently

sky/sdk/lib/widgets/scaffold.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'dart:sky' as sky;
 
-import '../rendering/box.dart';
-import '../rendering/object.dart';
-import '../theme/view_configuration.dart';
-import 'widget.dart';
+import 'package:sky/rendering/box.dart';
+import 'package:sky/rendering/object.dart';
+import 'package:sky/theme/view_configuration.dart';
+import 'package:sky/widgets/widget.dart';
 
 // Slots are painted in this order and hit tested in reverse of this order
 enum ScaffoldSlots {
   body,
   statusBar,
   toolbar,
   snackBar,
   floatingActionButton,
   drawer
 }
@@ skipping 202 matching lines @@
     super.syncRenderObject(old);
     for (ScaffoldSlots slot in ScaffoldSlots.values) {
       Widget widget = _slots[slot];
       _slots[slot] = syncChild(widget, old is Scaffold ? old._slots[slot] : null, slot);
       assert((_slots[slot] == null) == (widget == null));
       assert(_slots[slot] == null || _slots[slot].parent == this);
     }
   }
 
 }